This SCOR program is basically a multidisciplinary approach to the study of certain aspects of the acute respiratory distress syndrome (RDS) in infants. The major goals of the program are: A. To obtain more information on the natural history of the condition. B. To study physiological characteristics of metabolism of infants with respiratory distress syndrome. C. To study factors leading to bacterial superinfection in RDS, especially in infants receiving mechanical ventilation and intravenous alimentation and to develop physiological methods of preventing such superinfection. D. To study certain possible etiological factors in RDS: amino acid composition of lung elastin; levels of serum enzyme inhibitors; filtration coefficient of pulmonary capillaries. The program is organized into 7 segments, a core administration and six approved projects. These segments have been designated Scopes A to G.